\documentclass[11pt,a5paper,footinclude=true,headinclude=true]{scrbook} % KOMA-Script book
\usepackage{multirow}

\begin{document}

\begin{center}
    \begin{tabular}{|c|c|c|c|}
        \hline
        Type & \multicolumn{2}{c|}{Register} & Purpose \\\hline\hline
        \multirow{16}{*}{General Purpose} & \multirow{2}{*}{ax} & ah & \multirow{2}{*}{Arithmetic} \\
                                        \cline{3-3}
                                        & & al & \\
                                        \cline{2-4}
                                        & \multirow{2}{*}{bx} & bh & \multirow{2}{*}{Base} \\
                                        \cline{3-3}
                                        & & bl & \\
                                        \cline{2-4}
                                        & \multirow{2}{*}{cx} & ch & \multirow{2}{*}{Counter} \\
                                        \cline{3-3}
                                        & & cl & \\
                                        \cline{2-4}
                                        & \multirow{2}{*}{dx} & dh & \multirow{2}{*}{Data} \\
                                        \cline{3-3}
                                        & & dl & \\
                                        \cline{2-4}
                                        & \multicolumn{2}{c|}{\multirow{2}{*}{sp}} & \multirow{2}{*}{Stack Pointer} \\
                                        & \multicolumn{2}{c|}{} & \\
                                        \cline{2-4}
                                        & \multicolumn{2}{c|}{\multirow{2}{*}{bp}} & \multirow{2}{*}{Base Pointer} \\
                                        & \multicolumn{2}{c|}{} & \\
                                        \cline{2-4}
                                        & \multicolumn{2}{c|}{\multirow{2}{*}{si}} & \multirow{2}{*}{Source Index} \\
                                        & \multicolumn{2}{c|}{} & \\
                                        \cline{2-4}
                                        & \multicolumn{2}{c|}{\multirow{2}{*}{di}} & \multirow{2}{*}{Destination Index} \\
                                        & \multicolumn{2}{c|}{} & \\
        \hline
        \multirow{6}{*}{Segment}        & \multicolumn{2}{c|}{ss} & Stack Segment \\
                                        \cline{2-4}
                                        & \multicolumn{2}{c|}{cs} & Code Segment \\
                                        \cline{2-4}
                                        & \multicolumn{2}{c|}{ds} & Data Segment \\
                                        \cline{2-4}
                                        & \multicolumn{2}{c|}{es} & Extra Segment \\
                                        \cline{2-4}
                                        & \multicolumn{2}{c|}{fs} & Extra Segment \\
                                        \cline{2-4}
                                        & \multicolumn{2}{c|}{gs} & Extra Segment \\
        \hline
    \end{tabular}
\end{center}

\end{document}
